src/libsystemd-network/dhcp6-option.c

   1 /***
   2   This file is part of systemd.
   3
   4   Copyright (C) 2014-2015 Intel Corporation. All rights reserved.
   5
   6   systemd is free software; you can redistribute it and/or modify it
   7   under the terms of the GNU Lesser General Public License as published by
   8   the Free Software Foundation; either version 2.1 of the License, or
   9   (at your option) any later version.
  10
  11   systemd is distributed in the hope that it will be useful, but
  12   WITHOUT ANY WARRANTY; without even the implied warranty of
  13   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  14   Lesser General Public License for more details.
  15
  16   You should have received a copy of the GNU Lesser General Public License
  17   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  18 ***/
  19
  20 #include <errno.h>
  21 #include <netinet/in.h>
  22 #include <string.h>
  23
  24 #include "sd-dhcp6-client.h"
  25
  26 #include "alloc-util.h"
  27 #include "dhcp6-internal.h"
  28 #include "dhcp6-protocol.h"
  29 #include "dns-domain.h"
  30 #include "sparse-endian.h"
  31 #include "strv.h"
  32 #include "unaligned.h"
  33 #include "util.h"
  34
  35 #define DHCP6_OPTION_IA_NA_LEN                  12
  36 #define DHCP6_OPTION_IA_TA_LEN                  4
  37
  38 typedef struct DHCP6Option {
  39         be16_t code;
  40         be16_t len;
  41         uint8_t data[];
  42 } _packed_ DHCP6Option;
  43
  44 static int option_append_hdr(uint8_t **buf, size_t *buflen, uint16_t optcode,
  45                              size_t optlen) {
  46         DHCP6Option *option = (DHCP6Option*) *buf;
  47
  48         assert_return(buf, -EINVAL);
  49         assert_return(*buf, -EINVAL);
  50         assert_return(buflen, -EINVAL);
  51
  52         if (optlen > 0xffff || *buflen < optlen + sizeof(DHCP6Option))
  53                 return -ENOBUFS;
  54
  55         option->code = htobe16(optcode);
  56         option->len = htobe16(optlen);
  57
  58         *buf += sizeof(DHCP6Option);
  59         *buflen -= sizeof(DHCP6Option);
  60
  61         return 0;
  62 }
  63
  64 int dhcp6_option_append(uint8_t **buf, size_t *buflen, uint16_t code,
  65                         size_t optlen, const void *optval) {
  66         int r;
  67
  68         assert_return(optval || optlen == 0, -EINVAL);
  69
  70         r = option_append_hdr(buf, buflen, code, optlen);
  71         if (r < 0)
  72                 return r;
  73
  74         memcpy_safe(*buf, optval, optlen);
  75
  76         *buf += optlen;
  77         *buflen -= optlen;
  78
  79         return 0;
  80 }
  81
  82 int dhcp6_option_append_ia(uint8_t **buf, size_t *buflen, DHCP6IA *ia) {
  83         uint16_t len;
  84         uint8_t *ia_hdr;
  85         size_t ia_buflen, ia_addrlen = 0;
  86         DHCP6Address *addr;
  87         int r;
  88
  89         assert_return(buf && *buf && buflen && ia, -EINVAL);
  90
  91         switch (ia->type) {
  92         case SD_DHCP6_OPTION_IA_NA:
  93                 len = DHCP6_OPTION_IA_NA_LEN;
  94                 break;
  95
  96         case SD_DHCP6_OPTION_IA_TA:
  97                 len = DHCP6_OPTION_IA_TA_LEN;
  98                 break;
  99
 100         default:
 101                 return -EINVAL;
 102         }
 103
 104         if (*buflen < len)
 105                 return -ENOBUFS;
 106
 107         ia_hdr = *buf;
 108         ia_buflen = *buflen;
 109
 110         *buf += sizeof(DHCP6Option);
 111         *buflen -= sizeof(DHCP6Option);
 112
 113         memcpy(*buf, &ia->id, len);
 114
 115         *buf += len;
 116         *buflen -= len;
 117
 118         LIST_FOREACH(addresses, addr, ia->addresses) {
 119                 r = option_append_hdr(buf, buflen, SD_DHCP6_OPTION_IAADDR,
 120                                       sizeof(addr->iaaddr));
 121                 if (r < 0)
 122                         return r;
 123
 124                 memcpy(*buf, &addr->iaaddr, sizeof(addr->iaaddr));
 125
 126                 *buf += sizeof(addr->iaaddr);
 127                 *buflen -= sizeof(addr->iaaddr);
 128
 129                 ia_addrlen += sizeof(DHCP6Option) + sizeof(addr->iaaddr);
 130         }
 131
 132         r = option_append_hdr(&ia_hdr, &ia_buflen, ia->type, len + ia_addrlen);
 133         if (r < 0)
 134                 return r;
 135
 136         return 0;
 137 }
 138
 139
 140 static int option_parse_hdr(uint8_t **buf, size_t *buflen, uint16_t *optcode, size_t *optlen) {
 141         DHCP6Option *option = (DHCP6Option*) *buf;
 142         uint16_t len;
 143
 144         assert_return(buf, -EINVAL);
 145         assert_return(optcode, -EINVAL);
 146         assert_return(optlen, -EINVAL);
 147
 148         if (*buflen < sizeof(DHCP6Option))
 149                 return -ENOMSG;
 150
 151         len = be16toh(option->len);
 152
 153         if (len > *buflen)
 154                 return -ENOMSG;
 155
 156         *optcode = be16toh(option->code);
 157         *optlen = len;
 158
 159         *buf += 4;
 160         *buflen -= 4;
 161
 162         return 0;
 163 }
 164
 165 int dhcp6_option_parse(uint8_t **buf, size_t *buflen, uint16_t *optcode,
 166                        size_t *optlen, uint8_t **optvalue) {
 167         int r;
 168
 169         assert_return(buf && buflen && optcode && optlen && optvalue, -EINVAL);
 170
 171         r = option_parse_hdr(buf, buflen, optcode, optlen);
 172         if (r < 0)
 173                 return r;
 174
 175         if (*optlen > *buflen)
 176                 return -ENOBUFS;
 177
 178         *optvalue = *buf;
 179         *buflen -= *optlen;
 180         *buf += *optlen;
 181
 182         return 0;
 183 }
 184
 185 int dhcp6_option_parse_ia(uint8_t **buf, size_t *buflen, uint16_t iatype,
 186                           DHCP6IA *ia) {
 187         int r;
 188         uint16_t opt, status;
 189         size_t optlen;
 190         size_t iaaddr_offset;
 191         DHCP6Address *addr;
 192         uint32_t lt_t1, lt_t2, lt_valid, lt_pref, lt_min = ~0;
 193
 194         assert_return(ia, -EINVAL);
 195         assert_return(!ia->addresses, -EINVAL);
 196
 197         switch (iatype) {
 198         case SD_DHCP6_OPTION_IA_NA:
 199
 200                 if (*buflen < DHCP6_OPTION_IA_NA_LEN + sizeof(DHCP6Option) +
 201                     sizeof(addr->iaaddr)) {
 202                         r = -ENOBUFS;
 203                         goto error;
 204                 }
 205
 206                 iaaddr_offset = DHCP6_OPTION_IA_NA_LEN;
 207                 memcpy(&ia->id, *buf, iaaddr_offset);
 208
 209                 lt_t1 = be32toh(ia->lifetime_t1);
 210                 lt_t2 = be32toh(ia->lifetime_t2);
 211
 212                 if (lt_t1 && lt_t2 && lt_t1 > lt_t2) {
 213                         log_dhcp6_client(client, "IA T1 %ds > T2 %ds",
 214                                          lt_t1, lt_t2);
 215                         r = -EINVAL;
 216                         goto error;
 217                 }
 218
 219                 break;
 220
 221         case SD_DHCP6_OPTION_IA_TA:
 222                 if (*buflen < DHCP6_OPTION_IA_TA_LEN + sizeof(DHCP6Option) +
 223                     sizeof(addr->iaaddr)) {
 224                         r = -ENOBUFS;
 225                         goto error;
 226                 }
 227
 228                 iaaddr_offset = DHCP6_OPTION_IA_TA_LEN;
 229                 memcpy(&ia->id, *buf, iaaddr_offset);
 230
 231                 ia->lifetime_t1 = 0;
 232                 ia->lifetime_t2 = 0;
 233
 234                 break;
 235
 236         default:
 237                 r = -ENOMSG;
 238                 goto error;
 239         }
 240
 241         ia->type = iatype;
 242
 243         *buflen -= iaaddr_offset;
 244         *buf += iaaddr_offset;
 245
 246         while ((r = option_parse_hdr(buf, buflen, &opt, &optlen)) >= 0) {
 247
 248                 switch (opt) {
 249                 case SD_DHCP6_OPTION_IAADDR:
 250
 251                         addr = new0(DHCP6Address, 1);
 252                         if (!addr) {
 253                                 r = -ENOMEM;
 254                                 goto error;
 255                         }
 256
 257                         LIST_INIT(addresses, addr);
 258
 259                         memcpy(&addr->iaaddr, *buf, sizeof(addr->iaaddr));
 260
 261                         lt_valid = be32toh(addr->iaaddr.lifetime_valid);
 262                         lt_pref = be32toh(addr->iaaddr.lifetime_valid);
 263
 264                         if (!lt_valid || lt_pref > lt_valid) {
 265                                 log_dhcp6_client(client, "IA preferred %ds > valid %ds",
 266                                                  lt_pref, lt_valid);
 267                                 free(addr);
 268                         } else {
 269                                 LIST_PREPEND(addresses, ia->addresses, addr);
 270                                 if (lt_valid < lt_min)
 271                                         lt_min = lt_valid;
 272                         }
 273
 274                         break;
 275
 276                 case SD_DHCP6_OPTION_STATUS_CODE:
 277                         if (optlen < sizeof(status))
 278                                 break;
 279
 280                         status = (*buf)[0] << 8 | (*buf)[1];
 281                         if (status) {
 282                                 log_dhcp6_client(client, "IA status %d",
 283                                                  status);
 284                                 r = -EINVAL;
 285                                 goto error;
 286                         }
 287
 288                         break;
 289
 290                 default:
 291                         log_dhcp6_client(client, "Unknown IA option %d", opt);
 292                         break;
 293                 }
 294
 295                 *buflen -= optlen;
 296                 *buf += optlen;
 297         }
 298
 299         if (r == -ENOMSG)
 300                 r = 0;
 301
 302         if (!ia->lifetime_t1 && !ia->lifetime_t2) {
 303                 lt_t1 = lt_min / 2;
 304                 lt_t2 = lt_min / 10 * 8;
 305                 ia->lifetime_t1 = htobe32(lt_t1);
 306                 ia->lifetime_t2 = htobe32(lt_t2);
 307
 308                 log_dhcp6_client(client, "Computed IA T1 %ds and T2 %ds as both were zero",
 309                                  lt_t1, lt_t2);
 310         }
 311
 312         if (*buflen)
 313                 r = -ENOMSG;
 314
 315 error:
 316         *buf += *buflen;
 317         *buflen = 0;
 318
 319         return r;
 320 }
 321
 322 int dhcp6_option_parse_ip6addrs(uint8_t *optval, uint16_t optlen,
 323                                 struct in6_addr **addrs, size_t count,
 324                                 size_t *allocated) {
 325
 326         if (optlen == 0 || optlen % sizeof(struct in6_addr) != 0)
 327                 return -EINVAL;
 328
 329         if (!GREEDY_REALLOC(*addrs, *allocated,
 330                             count * sizeof(struct in6_addr) + optlen))
 331                 return -ENOMEM;
 332
 333         memcpy(*addrs + count, optval, optlen);
 334
 335         count += optlen / sizeof(struct in6_addr);
 336
 337         return count;
 338 }
 339
 340 int dhcp6_option_parse_domainname(const uint8_t *optval, uint16_t optlen, char ***str_arr) {
 341         size_t pos = 0, idx = 0;
 342         _cleanup_strv_free_ char **names = NULL;
 343         int r;
 344
 345         assert_return(optlen > 1, -ENODATA);
 346         assert_return(optval[optlen - 1] == '\0', -EINVAL);
 347
 348         while (pos < optlen) {
 349                 _cleanup_free_ char *ret = NULL;
 350                 size_t n = 0, allocated = 0;
 351                 bool first = true;
 352
 353                 for (;;) {
 354                         uint8_t c;
 355
 356                         c = optval[pos++];
 357
 358                         if (c == 0)
 359                                 /* End of name */
 360                                 break;
 361                         else if (c <= 63) {
 362                                 const char *label;
 363
 364                                 /* Literal label */
 365                                 label = (const char *)&optval[pos];
 366                                 pos += c;
 367                                 if (pos > optlen)
 368                                         return -EMSGSIZE;
 369
 370                                 if (!GREEDY_REALLOC(ret, allocated, n + !first + DNS_LABEL_ESCAPED_MAX)) {
 371                                         r = -ENOMEM;
 372                                         goto fail;
 373                                 }
 374
 375                                 if (first)
 376                                         first = false;
 377                                 else
 378                                         ret[n++] = '.';
 379
 380                                 r = dns_label_escape(label, c, ret + n, DNS_LABEL_ESCAPED_MAX);
 381                                 if (r < 0)
 382                                         goto fail;
 383
 384                                 n += r;
 385                                 continue;
 386                         } else {
 387                                 r = -EBADMSG;
 388                                 goto fail;
 389                         }
 390                 }
 391
 392                 if (!GREEDY_REALLOC(ret, allocated, n + 1)) {
 393                         r = -ENOMEM;
 394                         goto fail;
 395                 }
 396
 397                 ret[n] = 0;
 398
 399                 r = strv_extend(&names, ret);
 400                 if (r < 0)
 401                         goto fail;
 402
 403                 idx++;
 404         }
 405
 406         *str_arr = names;
 407         names = NULL;
 408
 409         return idx;
 410
 411 fail:
 412         return r;
 413 }